1. Field of the Invention
The present invention generally relates to a printing machine which can selectively use two or more types of printing heads having different kinds of and layouts of type faces. More particularly, this invention relates to a printing machine characterized by its printing of ruled lines (or simple lines).
2. Description of the Related Art
Conventionally, printing machines, such as typewriters or printers, have been proposed which can print lines as well as characters in order to prepare a fine table. For instance, a printing machine is known which has a daisy wheel with type faces for line printing and prints lines in accordance with a key operation (see Published Examined Japanese Patent Application No. 61-15831). Normally, printing machines, such as typewriters or word processors, can use any of several kinds of replaceable daisy wheels with different layouts of type faces as desired. There are a plurality of daisy wheels having different layouts of type faces associated with countries to which printers are to be exported. The daisy wheels include an English wheel for the U.S.A. or other English speaking countries, an international wheel with the type face layout common to all the countries, which permits printing of German, Spanish, etc. in addition to English, and a symbol wheel having only symbol type faces.
In general, due to differences in the kinds of type faces that should be provided, key operations and customs, the layout of non-alphanumeric characters are varied dependant on the particular daisy wheel used. Therefore, data prepared specifically for a certain daisy wheel, if saved in an internal memory of the printing machine or a floppy disk, cannot be used at all when a different daisy wheel is in use. This requires that different data be prepared in advance for different daisy wheels.
In preparing English text and German text, these texts should naturally be prepared separately. However, table layout data should be useable irrespective of whether the language in use is English or German. This is because it is often desirable to use the same table regardless of the language in use. Line data, unlike words, however, should be input while counting the number of characters between lines in light of the size of the table. Entering the line data is very troublesome compared with text input. According to the conventional printing machines, as described above, line data should be prepared separately for individual daisy wheels, requiring more work to prepare a table and thus making the work tiresome.
Type faces equipped on a daisy wheel for lines include horizontal and vertical single lines, such as "--" and ".vertline." and horizontal and vertical double lines, such as "=" and ".parallel.". As the kinds of type faces on the individual daisy wheels and the layouts of the type faces differ due to the difference in customs in the countries where the daisy wheels are used, it often happens that one daisy wheel has a type face for a vertical double line while the others do not.
With no type face for a vertical double line on a daisy wheel, there would arise the following problem in preparing a table as shown in FIG. 14A (the table horizontally divided into three sections by vertical double lines with the center and right sections each further bisected by a vertical single line). A non-line character, such as "$," would be printed where the vertical double lines should be printed. In this case, as "$" is printed where the double lines should be, even when one wishes to simply print a numeral "1,000," "$1,000," an amount of money, would be printed against the operator's intention.
One proposed solution to the above shortcoming suggests inhibiting printing a double vertical line if the daisy wheel in use does not have an appropriate type face. However a table printed in this manner (FIG. 14C) would be quite different from the intended one (FIG. 14A).